Method and apparatus for applying energy to biological tissue including the use of tumescent tissue compression

ABSTRACT

An electrode catheter is introduced into a hollow anatomical structure, such as a vein, and is positioned at a treatment site within the structure. Tumescent fluid is injected into the tissue surrounding the treatment site to produce tumescence of the surrounding tissue which then compresses the vein. The solution may include an anesthetic, and may further include a vasoconstrictive drug that shrinks blood vessels. The tumescent swelling in the surrounding tissue causes the hollow anatomical structure to become compressed, thereby exsanguinating the treatment site. Energy is applied by an electrode catheter in apposition with the vein wall to create a heating effect. The heating effect causes the hollow anatomical structure to become molded and durably assume the compressed dimensions caused by the tumescent technique. The electrode catheter can be moved within the structure so as to apply energy to a large section of the hollow anatomic structure. In a further aspect, the location of the electrodes is determined by impedance monitoring. Also, temperature sensors at the treatment site are averaged to determine the site temperature.

This application is a continuation of Ser. No. 10/872,646, filed Jun.21, 2004, which is a continuation of Ser. No. 09/899,885 (now U.S. Pat.No. 6,752,803), filed Jul. 6, 2001, which is a continuation of Ser. No.09/267,127 (now U.S. Pat. No. 6,258,084), filed Mar. 10, 1999, which isa continuation-in-part of Ser. No. 09/138,472 (now U.S. Pat. No.6,179,832), filed Aug. 21, 1998, which is a continuation-in-part of Ser.No. 08/927,251 (now U.S. Pat. No. 6,200,312), filed Sep. 11, 1997.

BACKGROUND

The invention relates generally to a method and apparatus for applyingenergy to shrink a hollow anatomical structure, such as a fallopian tubeor a vein, including but not limited to, superficial and perforatorveins, hemorrhoids, and esophageal varices. In some particular aspects,the invention relates to a method for compressing an anatomicalstructure prior to the application of energy and apparatus including anelectrode device having multiple leads for applying energy to thecompressed structure to cause it to durably assume its compressed form.

The human venous system of the lower limbs consists essentially of thesuperficial venous system and the deep venous system with perforatingveins connecting the two systems. The superficial system includes thelong or great saphenous vein and the short saphenous vein. The deepvenous system includes the anterior and posterior tibial veins whichunite to form the popliteal vein, which in turn becomes the femoral veinwhen joined by the short saphenous vein.

The venous system contains numerous one-way valves for directing bloodflow back to the heart such as those valves 20 located in the vein 22shown in FIG. 1. The arrow leading out the top of the vein representsthe antegrade flow of blood back to the heart. Venous valves are usuallybicuspid valves, with each cusp 24 forming a sack or reservoir 26 forblood which, under retrograde blood pressure, forces the free surfacesof the cusps together to prevent retrograde flow of the blood and allowsonly antegrade blood flow to the heart. Competent venous valves preventretrograde flow as blood is pushed forward through the vein lumen andback to the heart. When an incompetent valve 28 is in the flow path, thevalve is unable to close because the cusps do not form a proper seal andretrograde flow of the blood cannot be stopped. When a venous valvefails, increased strain and pressure occur within the lower venoussections and overlying tissues, sometimes leading to additional valvularfailure. Incompetent valves may result from the stretching of dilatedveins. As the valves fail, increased pressure is imposed on the lowerveins and the lower valves of the vein, which in turn exacerbates thefailure of these lower valves. A cross-sectional perspective view of adilated vein with an incompetent valve 28 taken along lines 2-2 of FIG.1 is illustrated in FIG. 2. The valve cusps 24 can experience someseparation at the commissure due to the thinning and stretching of thevein wall at the cusps. Two venous conditions which often result fromvalve failure are varicose veins and more symptomatic chronic venousinsufficiency.

The varicose vein condition includes dilation and tortuosity of thesuperficial veins of the lower limbs, resulting in unsightlydiscoloration, pain, swelling, and possibly ulceration. Varicose veinsoften involve incompetence of one or more venous valves, which allowreflux of blood within the superficial system. This can also worsen deepvenous reflux and perforator reflux. Current treatments of veininsufficiency include surgical procedures such as vein stripping,ligation, and occasionally, vein-segment transplant.

Chronic venous insufficiency involves an aggravated condition ofvaricose veins which may be caused by degenerative weakness in the veinvalve segment, or by hydrodynamic forces acting on the tissues of thebody, such as the legs, ankles, and feet. As the valves in the veinsfail, the hydrostatic pressure increases on the next venous valves down,causing those veins to dilate. As this continues, more venous valveswill eventually fail. As they fail, the effective height of the columnof blood above the feet and ankles grows, and the weight and hydrostaticpressure exerted on the tissues of the ankle and foot increases. Whenthe weight of that column reaches a critical point as a result of thevalve failures, ulcerations of the ankle begin to form, which start deepand eventually come to the surface. These ulcerations do not heal easilybecause of poor venous circulation due to valvular incompetence in thedeep venous system and other vein systems.

Other related venous conditions include dilated hemorrhoids andesophageal varices. Pressure and dilation of the hemorrhoid venousplexus may cause internal hemorrhoids to dilate and/or prolapse and beforced through the anal opening. If a hemorrhoid remains prolapsed,considerable discomfort, including itching and bleeding, may result. Thevenous return from these prolapsed hemorrhoids becomes obstructed by theanal sphincters, which gives rise to a strangulated hemorrhoid.Thromboses result where the blood within the prolapsed vein becomesclotted. This extremely painful condition can cause edema andinflammation.

Varicose veins called esophageal varices can form in the venous systemwith submucosa of the lower esophagus, and bleeding can occur from thedilated veins. Bleeding or hemorrhaging may result from esophagealvarices, which can be difficult to stop and, if untreated, could developinto a life threatening condition. Such varices erode easily, and leadto a massive gastrointestinal hemorrhage.

Ligation of a fallopian tube (tubal ligation) for sterilization or otherpurposes is typically performed by laparoscopy. A doctor severs thefallopian tube or tubes and ties the ends. External cauterization orclamps may also be used. General or regional anesthetic must be used.All of the above are performed from outside the fallopian tube.

Hemorrhoids and esophageal varices may be alleviated by intra-luminalligation. As used herein, “ligation” or “intra-luminal ligation”comprises the occlusion, collapse, or closure of a lumen or hollowanatomical structure by the application of energy from within the lumenor structure. As used herein, “ligation” or “intra-luminal ligation”includes electro-ligation. In the case of fallopian tube ligation, itwould be desirable to perform the ligation from within the fallopiantube itself (intra-fallopian tube) to avoid the trauma associated withexternal methods.

Ligation involves the cauterization or coagulation of a lumen usingenergy, such as that applied through an electrode device. An electrodedevice is introduced into the lumen and positioned so that it contactsthe lumen wall. Once properly positioned, RF energy is applied to thewall by the electrode device thereby causing the wall to shrink incross-sectional diameter. In the case of a vein, a reduction incross-sectional diameter of the vein, as for example from 5 mm (0.2 in)to 1 mm (0.04 in), significantly reduces the flow of blood through alumen and results in an effective occlusion. Although not required foreffective occlusion or ligation, the vein wall may completely collapsethereby resulting in a full-lumen obstruction that blocks the flow ofblood through the vein. Likewise, a fallopian tube may collapsesufficiently to effect a sterilization of the patient.

One apparatus for performing ligation includes a tubular shaft having anelectrode device attached at the distal tip. Running through the shaft,from the distal end to the proximal end, are electrical leads. At theproximal end of the shaft, the leads terminate at an electricalconnector, while at the distal end of the shaft the leads are connectedto the electrode device. The electrical connector provides the interfacebetween the leads and a power source, typically an RF generator. The RFgenerator operates under the guidance of a control device, usually amicroprocessor.

The ligation apparatus may be operated in either a monopolar or bipolarconfiguration. In the monopolar configuration, the electrode deviceconsists of an electrode that is either positively or negativelycharged. A return path for the current passing through the electrode isprovided externally from the body, as for example by placing the patientin physical contact with a large low-impedance pad. The current flowsbetween the ligation device and low impedance pad through the patient.In a bipolar configuration, the electrode device consists of a pair ofelectrodes having different potentials (such as a pair ofoppositely-charged electrodes) of approximately equal size, separatedfrom each other, such as by a dielectric material or by a spatialrelationship. Accordingly, in the bipolar mode, the return path forcurrent is provided by an electrode or electrodes of the electrodedevice itself. The current flows from one electrode, through the tissue,and returns by way of the another electrode.

To protect against tissue damage, i.e., charring, due to cauterizationcaused by overheating, a temperature sensing device is typicallyattached to the electrode device, although it may be located elsewhere.The temperature sensing device may be a thermocouple that monitors thetemperature of the venous tissue. The thermocouple interfaces with theRF generator and the controller through the shaft and provideselectrical signals to the controller which monitors the temperature andadjusts the energy applied to the tissue through the electrode deviceaccordingly.

The overall effectiveness of a ligation apparatus is largely dependenton the electrode device contained within the apparatus. Monopolar andbipolar electrode devices that comprise solid devices having a fixedshape and size can limit the effectiveness of the ligating apparatus forseveral reasons. Firstly, a fixed-size electrode device typicallycontacts the vein wall at only one point or a limited arc on thecircumference or inner diameter of the vein wall. As a result, theapplication of RF energy is highly concentrated within the contactingvenous tissue, while the flow of RF current through the remainder of thevenous tissue is disproportionately weak. Accordingly, the regions ofthe vein wall near the area of contact collapse at a faster rate thanother regions of the vein wall, resulting in non-uniform shrinkage ofthe vein lumen. Furthermore, the overall strength of the occlusion maybe inadequate and the lumen may eventually reopen. To avoid aninadequate occlusion, RF energy must be applied for an extended periodof time so that the current flows through the tissue, including throughthe tissue not in contact with the electrode, generating thermal energyand causing the tissue to shrink sufficiently. Extended applications ofenergy have a greater possibility of increasing the temperature of theblood to an unacceptable level and may result in a significant amount ofheat-induced coagulum forming on the electrode and in the vein which isnot desirable. Furthermore, it is possible for the undesirable coagulumto form when utilizing an expandable electrode as well. This problem canbe prevented by exsanguination of the vein prior to the treatment, aswell as through the use of temperature-regulated power delivery. As usedherein, “exsanguination” comprises the removal of all or somesignificant portion of blood in a particular area.

Secondly, the effectiveness of a ligating apparatus having a fixed-sizeelectrode device is limited to certain sized veins. An attempt to ligatea vein having a diameter that is substantially greater than thefixed-size electrode device can result in not only non-uniform heatingof the vein wall as just described, but also insufficient shrinkage ofthe vein diameter. The greater the diameter of the vein relative to thediameter of the electrode device, the weaker the energy applied to thevein wall at points distant from the point of electrode contact. Also,larger diameter veins must shrink a larger percentage for effectiveocclusion to occur. Accordingly, the vein wall is likely to notcompletely collapse prior to the venous tissue becoming over-cauterizedat the point of electrode contact. While coagulation as such mayinitially occlude the vein, such occlusion may only be temporary in thatthe coagulated blood may eventually dissolve recanalizing the vein. Onesolution for this inadequacy is an apparatus having interchangeableelectrode devices with various diameters. Another solution is to have aset of catheters having different sizes so that one with the correctsize for the diameter of the target vein will be at hand when needed.Such solutions, however, are both economically inefficient and can betedious to use. It is desirable to use a single catheter device that isusable with a large range of sizes of lumina.

A technique of reducing the diameter of the lumen of a vein at leastclose to the final desired diameter before applying energy to the veinhas been found to aid in the efficiency of these types of procedures.The pre-reduction in vein diameter assists in pre-shaping the vein to bemolded into a ligated state. The compression also exsanguinates the veinand forces blood away from the treatment site, thus preventingcoagulation. One valuable technique employed is that of compressing thevein contained within a limb by applying external hydraulic pressure,via a pressure tourniquet, to the limb. Unfortunately there are someareas of the body to which a pressure tourniquet cannot be applied, suchas the sapheno-femoral junction, which is above the thigh proximate thegroin area. Furthermore, there are sites where a pressure tourniquet maybe ineffective such as: the popliteal junction and other areas aroundthe knee; and the ankle area (typically the posterior arch vein and someof the lower cockett perforators).

There exists a technique referred to as tumescent anesthesia that hasbeen used in connection with liposuction procedures. The word“tumescent” means swollen or firm. This technique is accomplished bysubcutaneously delivering into target fatty tissue a large volume ofsaline solution containing diluted Lidocaine and Epinephrine(adrenaline), a vasoconstrictive drug. The injected area then becomeslocally anesthetized, and the adrenaline temporarily constricts thecapillaries and other blood vessels. The tumescence-inducing fluid, or“tumescent fluid” is injected under pressure which causes the targetfatty tissue to become swollen and firm. The tumescent fluid istypically pumped into the pocket of fat in order to numb the area,loosen the fat, and constrict the blood vessels to minimize bleeding orbruising in a liposuction procedure. The anesthetic and other agents inthe tumescent solution should be allowed sufficient time to diffuse andtake full effect throughout the target tissue. After surgery, patientsmay leave without assistance, and often return to their regular routinewithin several days. With the tumescent technique, postoperativediscomfort is significantly reduced. The local anesthesia often remainsin the treated tissue for 16 hours after surgery. Employing a techniqueof utilizing tumescent anesthesia in conjunction with ligation or radiallumen shrinkage less than ligation may provide benefits.

Although described above in terms of a vein, the concepts are generallyapplicable to other hollow anatomical structures in the body as well.The above description has been generally confined to veins inconsideration of avoiding unnecessary repetition.

Hence those skilled in the art have recognized a need for an improvedmethod and apparatus that can be used on areas of the body to shrink andligate hollow anatomical structures. A need has also been recognized foran improved method and apparatus to pre-compress and exsanguinate ahollow anatomical structure while providing anesthetic and insulationbenefits during the radial shrinkage of the hollow anatomical structure.The invention fulfills these needs and others.

SUMMARY OF THE INVENTION

The present invention is directed to a method and apparatus for applyingenergy to a hollow anatomical structure such as a vein, to shrink thestructure. In a more detailed aspect, the invention is directed topre-compressing and exsanguinating a hollow anatomical structure whileproviding anesthetic and insulation benefits during a procedure ofshrinking the hollow anatomical structure.

In another aspect of the present invention, a method comprises providingfluid to tissue surrounding a hollow anatomical structure to inducetumescence of the tissue and consequent compression of the hollowanatomical structure during a procedure of applying energy to the hollowanatomical structure from within the structure. In a more detailedaspect, the method comprises introducing into the hollow anatomicalstructure a catheter having a working end and at least one electrode atthe working end; placing the electrode into contact with the inner wallof the pre-compressed hollow anatomical structure and applying energy tothe hollow anatomical structure at the treatment site via the electrodeuntil the hollow anatomical structure durably assumes dimensions lessthan or equal to the pre-compressed dimensions caused by the injectionof the solution into the tissue.

In another aspect in accordance with the invention, tumescent fluid isinjected in the tissue surrounding the hollow anatomical structure alonga selected length of the hollow anatomical structure. The electrode isthen moved along a site within the selected length while continuouslyapplying energy to result in a lengthy occlusion. In another approach,after an initial application of energy to one site internal to thehollow anatomical structure within the selected length, the electrode ismoved down a given length of the hollow anatomical structure and energyis applied at that adjacent site. For the site where energy is applied,the hollow anatomical structure durably assumes dimensions less than orequal to the pre-compressed dimensions caused by the injection of thesolution into the tissue.

In a more detailed aspect, tumescent anesthesia fluid is injected orotherwise provided to tissue contiguous with a vein to compress the veinto about a desired final diameter. A catheter having an energyapplication device, such as expandable electrodes, is introducedinternal to the vein at a site within the compressed portion of the veinand energy is applied to the internal vein wall by the applicationdevice. Sufficient energy is applied to cause the vein to durably assumethe compressed diameter such that when the effects of the tumescentanesthesia fluid are dissipated, the vein retains the compresseddiameter.

Alternate means to prevent coagulum formation include fluid displacementof blood at the treatment site, or exsanguination by inducingself-constriction of the vessel. In the latter, self-constrictionincludes, but is not limited to, intraluminal delivery of avasoconstrictive drug. Self-constriction also aids in pre-shaping thevein for ligation, as discussed previously. If the fluid delivered tothe site is a sclerosant, the ligation effects would be furtherenhanced.

In further aspects, energy is applied to effectively occlude thetreatment site. Further, the energy application device is moved alongthe treatment site while performing the step of applying energy so as toresult in a lengthy occlusion of the treatment site. The treatment sitemay collapse around the energy application device as it is being moved.In yet further detail, fluid is delivered from within the hollowstructure to the treatment site. This fluid may be used to exsanguinatethe treatment site. Such fluid may be from the following group: saline;a vasoconstrictive agent; a sclerosing agent; a high impedance fluid;and heparin.

In another aspect, temperatures are sensed at two separate locations onthe energy application device, and the temperature signals are averagedto determine the temperature at the site. In further detailed aspects,electrical energy is applied to the inner wall of the treatment sitewith an electrode, the electrode being in apposition with the innerwall. With the electrode being in apposition with the inner wall, themethod further comprises the steps of applying electrical energy withthe electrode to effectively occlude the treatment site at theelectrode, and moving the electrode along the treatment site whilemaintaining the electrode in apposition with the vein wall whileperforming the step of applying energy to effectively occlude thetreatment site so as to result in a lengthy effective occlusion of thetreatment site. Sufficient energy is applied to collapse the hollowanatomical structure around the energy application device as it is beingmoved along the treatment site to result in a lengthy effectiveocclusion of the treatment site.

In yet a further aspect, apposition of the energy application devicewith the inner wall of the hollow anatomical structure is determined bymonitoring the impedance experienced by the energy application device.

These and other aspects and advantages of the present invention willbecome apparent from the following more detailed description, when takenin conjunction with the accompanying drawings which illustrate, by wayof example, embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of a vein having competent valvesand having a dilated section with incompetent venous valves in a lowerlimb which are to be treated in accordance with the present invention;

FIG. 2 shows a representative view of a venous section with anincompetent valve from FIG. 1 taken along lines 2-2 which is to betreated in accordance with the present invention;

FIG. 3 is a cross-sectional view of the vein of FIG. 1 after the veinhas been compressed, although not to full occlusion, by the injection ofa tumescent anesthesia fluid in tissue surrounding the vein showing acatheter including an expandable electrode device prior to theapplication of energy to the vein;

FIG. 4 is a diagram of an energy application system that may be used inconjunction with the method of the present invention, depicting apartial cutaway view of the first embodiment of the catheter showingboth the working end and the connecting end with an RF generator and amicroprocessor connected at the connection end;

FIG. 5 is a cross-sectional view of the working end of an embodiment ofa catheter in accordance with the invention depicting the electrodes ina fully retracted position;

FIG. 5 a is an end view of the working end of the embodiment of thecatheter taken along line 5 a-5 a of FIG. 5;

FIG. 6 is a cross-sectional view of the working end of the embodiment ofthe catheter of FIGS. 5 and 5 a depicting the electrodes in a fullyexpanded position;

FIG. 6 a is an end view of the working end of the embodiment of thecatheter taken along line 6 a-6 a of FIG. 6;

FIG. 7 is a cross-sectional view of a vein after the vein has beencompressed, although not to full occlusion, by tumescent anesthesiafluid, the vein containing the catheter of FIG. 5 with the electrodes inapposition with the vein;

FIG. 8 is a cross-sectional view of the compressed vein containing thecatheter of FIG. 5 where the vein is being ligated by the application ofenergy from the electrodes;

FIG. 9 is a partial cross-sectional view of the vein wall of FIG. 8showing a lengthy effective occlusion made by moving the electrodesalong the treatment site of the vein while maintaining the electrodes inapposition and continuing to apply energy to the vein wall.

FIG. 10 is a side view of an embodiment of an electrode catheter havingtwo pluralities of longitudinally-separated expandable electrodes in aretracted condition;

FIG. 11 is a side view of the embodiment of the electrode catheter ofFIG. 10 with both pluralities of the electrodes in expandedconfigurations; and

FIG. 12 is a partial cross-sectional view of the embodiment of anelectrode catheter of FIGS. 10 and 11.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in the exemplary drawings, the invention is directed toward theintravenous treatment of veins using a catheter to deliver at least oneelectrode to a venous treatment site. As used herein, like referencenumerals will designate similar elements in the various embodiments ofthe present invention to be discussed. In addition, unless otherwisenoted, the term “working end” will refer to the direction toward thetreatment site in the patient, and the term “connecting end” will referto the direction away from the treatment site in the patient. Theinvention will be described in relation to the treatment of the venoussystem of the lower limbs. It is to be understood, however, that theinvention is not limited thereto and may be employed intraluminally totreat veins in other areas of the body such as hemorrhoids, esophagealvarices, and venous-drainage-impotence of the penis. Furthermore,although the invention will be described as using RF energy from theelectrode, it is to be understood that other forms of energy such asmicrowaves, ultrasound, direct current, circulating heated fluid,radiant light, and lasers can be used, and that the thermal energygenerated from a resistive coil or curie point element may be used aswell.

Turning to FIG. 3, one preferred method of the present invention can beperformed using the catheter 30 to deliver an expandable electrodedevice 32 (partially shown) to a venous treatment site in order toligate the vein. Instead of compressing the tissue surrounding thetreatment site via a pressure tourniquet, a tumescent anesthesiatechnique can be used to inject a dilute anesthetic and vasoconstrictivesolution into the tissue surrounding the vein to be treated. Thetumescent solution preferably includes mostly saline solution, with alocal anesthetic such as Lidocaine, and a vasoconstrictive drug such asEpinephrine. The tumescent solution causes the surrounding tissue 34 tobecome swollen which compresses the vein 22, as indicated by the arrows,close to occlusion (in this case) or to occlusion. Sufficient tumescentsolution should be delivered into the tissue surrounding the vein tocompress and exsanguinate the vein. Before injecting the tumescentsolution, the catheter 30 is placed within the vein at the treatmentsite, with the expandable electrode device retracted.

The solution is typically infused with a peristaltic pump. However, 60cc or 100 cc syringes 35 can be used. Another alternative is an IV bagwith a pressure cuff. Large volumes are typically delivered into theperivenal area via a large cannula. Sites are typically located 10 cmapart down the leg. Usually there are four or five delivery sites. Theexternal result is a leg that appears inflated. The internal result iscompressed veins plus an anesthetized leg. The expandable electrodedevice is then expanded into apposition with the venous tissue aftercompression of the vein. Energy such as high frequency RF energy isapplied from the expandable electrode device to the venous tissue untilthe vein durably assumes dimensions less than or equal to the compresseddimensions caused by the injection of the tumescent solution into thetissue.

After completing the procedure for a selected venous section ortreatment site, the electrode may be retracted and the catheter moved toanother venous section where the ligation process is repeated.Ultrasound guidance can be used to monitor the progress of theprocedure.

One preferred embodiment of the catheter for delivering an expandableenergy application device or expandable electrode device 56 to thevenous treatment site is illustrated in FIG. 4. The catheter 30 includesan expandable energy application device 56 which in this embodiment,comprises an array of electrodes 58, an outer sheath 36 having a distalorifice 38 at its working end 40. The connector end 42 of the outersheath is attached to a handle 44 that includes electrical connector 46.The handle additionally includes a guide wire port 48. The connector 46is for interfacing with a power source, typically an RF generator 50,and a microprocessor controller 52. The power source and microprocessorcontroller are usually contained in one unit. The microprocessorcontroller controls the RF generator in response to external commandsand data from a temperature sensor 54, such as a thermocouple, ortemperature sensors that may be positioned at an intraluminal venoustreatment site.

The catheter 30 includes the expandable electrode device 56 that movesin and out of the outer sheath by way of the distal orifice 38 in thisembodiment, although in other embodiments the device 56 may expand fromand contract into the catheter 30 at other locations. The expandableelectrode device 56 includes a plurality of electrodes 58 which can beexpanded by moving the outer sheath 36 relative to the electrodes.Although FIG. 4 illustrates a plurality of electrodes 58 surrounding asingle central electrode, different electrode configurations may beused.

Contained within the outer sheath 36 is an inner sheath 60 or innermember as shown in the cutaway portion of FIG. 4. A fluid port 62communicates with the interior of the outer sheath. The catheter 30 canbe periodically flushed out with saline through the fluid port. Theflushing fluid can travel between the outer sheath and the inner sheath.The fluid port also allows for the delivery of drug therapies. Flushingout the catheter prevents the buildup of biological fluid, such asblood, within the catheter. The treatment area or site of the vein canbe flushed with a fluid such as saline, or a high impedance dielectricfluid, in order to evacuate blood from the treatment area of the vein soas to prevent the formation of coagulum or thrombosis. The use of a highimpedance dielectric fluid can minimize unintended heating effects awayfrom the treatment area. The dielectric fluid directs the current of RFenergy toward the vein wall. In addition, a vasoconstrictive agent maybe applied to shrink the vein, heparin may be applied for coagulationavoidance, and a sclerosing agent may be applied to assist in ligation.These drugs or agents may be applied before, during, or after thecatheter is used to heat the vein wall.

In one preferred embodiment, the catheter 30 includes a lumen whichbegins at the distal tip 55, proximate the working end 40, and runssubstantially along the axis of the inner member before terminating atthe guide wire port 48 of the handle 44. A guide wire can be introducedthrough the lumen of the catheter for use in guiding the catheter to thedesired treatment site. Where the catheter is sized to treat smallerveins, the outer diameter of the catheter may not allow for a fluidflush between the outer sheath and the inner sheath 60. However, a fluidflush can be introduced through the guide wire port 48 in such anembodiment.

Turning again to FIG. 4, an actuator 76 controls the extension of theelectrode device 56 through the distal orifice 38. The actuator may takethe form of a switch, lever 78, threaded control knob, or other suitablemechanism, and is preferably one that can provide fine control over themovement of the outer sheath 36 or the inner sheath 60, as the case maybe. In one embodiment of the invention, the actuator interfaces with theouter sheath to move it back and forth relative to the inner sheath. Inanother embodiment the actuator interfaces with the inner sheath to moveit back and forth relative to the outer sheath. The relative positionbetween the outer sheath and inner sheath is thus controlled, but othercontrol approaches may be used.

In a preferred embodiment of a catheter 90 is illustrated in FIG. 5. Aninner member 92 or sheath is contained within the outer sheath 94. Theinner sheath is preferably constructed from a flexible polymer such aspolymide, polyethylene, or nylon, and can travel the entire length ofthe catheter. The majority of the catheter should be flexible so as tonavigate the tortuous paths of the venous system. A hypotube having aflared distal end 98 and a circular cross-sectional shape is attachedover the distal end of the inner sheath 92. The hypotube 96 ispreferably no more than about two to three centimeters in length. Thehypotube acts as part of a conductive secondary lead 100. An uninsulatedconductive electrode sphere 102 is slipped over the hypotube. The flareddistal end of the hypotube prevents the electrode sphere from movingbeyond the distal end of the hypotube. The sphere is permanently affixedto the hypotube, such as by soldering the sphere both front and back onthe hypotube. The majority of the surface of the electrode sphereremains uninsulated. The remainder of the hypotube is preferablyinsulated so that the sphere-shaped distal end can act as the electrode.For example, the hypotube can be covered with an insulating materialsuch as a coating of parylene. The interior lumen of the hypotube islined by the inner sheath 92 which is attached to the flared distal endof the hypotube by adhesive such as epoxy.

Surrounding the secondary lead 100 are a plurality of primary leads 104that preferably have a flat rectangular strip shape and can act as arms.In one configuration, the strip shape is a width from 0.76 mm (0.03 in)to 1.00 mm (0.04 in) and a thickness of approximately 0.13 mm (0.005in.). As illustrated in FIG. 6, the plurality of primary leads 104 ispreferably connected to common conductive rings 106. This configurationmaintains the position of the plurality of primary leads, while reducingthe number of internal electrical connections. The conductive rings 106are attached to the inner sheath 92. The position of the rings and theprimary leads relative to the outer sheath 94 follows that of the innersheath. As earlier described, the hypotube 96 of the secondary lead isalso attached to the inner sheath. Two separate conductive rings can beused so that the polarity of different primary leads can be controlledseparately. For example, adjacent primary leads can be connected to oneof the two separate conductive rings so that the adjacent leads can beswitched to have either opposite polarities or the same polarity. Therings are preferably spaced closely together, but remain electricallyisolated from each other along the inner sheath. Both the rings and thehypotube are coupled with the inner sheath, and the primary leads thatare connected to the rings move together with the secondary lead whileremaining electrically isolated from the secondary lead. Epoxy oranother suitable adhesive can be used to attach the rings to the innersheath. The primary leads from the respective rings alternate with eachother along the circumference of the inner sheath. The insulation alongthe underside of the leads prevents an electrical short between therings. FIG. 6 a illustrates an end view of the working end of catheter90 taken along line 6 a-6 a of FIG. 6.

The conductive rings 106 and the primary leads 104 are attached togetherto act as cantilevers where the ring forms the base and the rectangularprimary leads operate as the cantilever arms. The primary leads areformed to have an arc or bend such that the primary leads act as armsthat tend to spring outwardly away from the catheter 90 and toward thesurrounding venous tissue. Insulation along the underside of the primaryleads and the conductive rings prevents unintended electrical couplingtherebetween. Alternately, the primary leads are formed straight andconnected to the conductive rings at an angle such that the primaryleads tend to expand or spring radially outward from the conductiverings. The angle at which the primary leads are attached to theconductive rings should be sufficient to force the primary distal endsand their electrodes 108 through blood and into apposition with the veinwall 80 but not enough to preclude vein shrinkage. In particular, theprimary leads 104 are formed with enough strength, and are mounted orbent such that they expand outwardly into apposition with the inner wallof the vein. However, the force they develop in an outward direction isnot strong enough to prevent radial shrinkage of the vein. As the veinshrinks, due to the heating caused by the energy delivered by theelectrodes 108, the shrinking vein causes a contraction of the primaryelectrodes. Due to the outward force constantly exerted by the primaryleads 104, the electrodes 108 remain in constant apposition with thevein wall as it shrinks.

Other properties of the primary leads, such as lead shape and insulationthickness, affect the push force of the lead against the vein wall andthe degree of arc or bend must be adjusted to compensate for thesefactors. The rectangular cross section of the primary leads can provideincreased stability in the lateral direction while allowing thenecessary bending in the radial direction. The primary leads are lesslikely to bend sideways when expanded outward due to the increased sizeof the rectangular lead in that sideways direction, and a uniformspacing between primary leads is more assured. Uniform spacing betweenthe primary leads and the distal ends promotes uniform heating aroundthe vein by the electrodes 108.

The distal ends of the primary leads 104 are uninsulated to act as theelectrodes 108 having a rounded shape. In the embodiment shown, theshape is convex which may take the form of a spoon or hemisphericalshape. The primary leads can be stamped to produce an integral shapedelectrode at the distal end of the primary leads. The uninsulated outerportion of the distal end of the electrodes 108 which are to come intoapposition with the wall of the vein is preferably rounded and convex.The flattened or non-convex inner portion of the distal end is insulatedto minimize any unintended thermal effect, such as on the surroundingblood in a vein. The distal ends of the electrodes 108 are configuredsuch that when the distal ends are forced toward the inner sheath 92, asshown in FIG. 5 a, the distal ends combine to form a substantiallyspherical shape with a profile smaller than the spherical electrode 102at the secondary distal end.

In one preferred embodiment as shown in FIG. 6, the electrodes 108comprise a convex, square center section with semi-circular ends. It hasbeen found that this “race track” configuration maximizes surface areaof contact for the electrodes 108 shown.

The outer sheath 94 can slide over and surround the primary andsecondary leads 100 and 104. The outer sheath includes an orifice 110which is dimensioned to have approximately the same size as thespherical electrode 102 at the secondary distal end. A close or snug fitbetween the spherical electrode 102 and the orifice 110 of the outersheath is achieved. This configuration provides an atraumatic tip forthe catheter 90. The spherical electrode 102 is preferably slightlylarger than the orifice 110. The inner diameter of the outer sheath isapproximately the same as the diameter of the reduced profile of thecombined primary distal end electrodes 108.

A fluid port (not shown) can communicate with the interior of the outersheath 94 so that fluid can be flushed between the outer sheath andinner sheath 92 as described above. Alternately, a fluid port cancommunicate with a central lumen 112 in the hypotube which can alsoaccept a guide wire for use in guiding the catheter to the desiredtreatment site. It is to be understood that another lumen can be formedin the catheter to deliver fluid to the treatment site. The deliveredfluid displaces or exsanguinates blood from the vein so as to avoidheating and coagulation of blood. The delivery of a dielectric fluidincreases the surrounding impedance so that RF energy is directed intothe tissue of the vein wall. An alternate fluid could be a sclerosingagent which could serve to displace blood or to further enhanceocclusion of the vein when applied before, during, or after energydelivery. The fluid can also include an anticoagulant such as heparinwhich can chemically discourage the coagulation of blood at thetreatment site. The catheter 90 can be periodically flushed with salinewhich can prevent the buildup of biological fluid, such as blood, withinthe catheter. The saline can be flushed through the central lumen 112 orbetween the inner and outer sheaths. If a central lumen is not desired,the lumen of the hypotube can be filled with solder.

The electrode device 114 can operate in either a bipolar or a monopolarconfiguration. When adjacent primary leads have opposite polarity, abipolar electrode operation is available. When the primary leads arecommonly charged a monopolar electrode operation is available incombination with a large return electrode pad placed in contact with thepatient. When the primary electrodes 108 are commonly charged or have afirst potential, and a secondary electrode 102 has an opposite polarityor different potential, a bipolar electrode operation is available. Moreor fewer leads may be used. The number of leads can be dependent on thesize or diameter of the vein to be treated, as described above.

Although not shown, it is to be understood that the catheter 90 caninclude one or more temperature sensors, such as thermocouples, mountedin place on an electrode 108 so that the sensor is substantially flushwith the exposed surface of the electrode 108. (The sensor is shown in araised position in the drawings for clarity of illustration only). Thetemperature sensor senses the temperature of the portion of the veinthat is in apposition with the exposed electrode 108 surface. The sensorprovides an indication of when shrinkage occurs (70 degrees C. orhigher). Application of RF energy from the electrodes 108 is halted orreduced when the monitored temperature reaches or exceeds the specifictemperature that was selected by the operator, such as the temperatureat which venous tissue begins to cauterize. Other techniques such asimpedance monitoring and ultrasonic pulse echoing can be utilized in anautomated system which shuts down or regulates the application of RFenergy from the electrodes to the venous section when sufficientshrinkage of the vein 22 is detected. This also helps to forestalloverheating of the vein.

Referring now to FIGS. 7 and 8, in the operation of this embodiment of acatheter 90, the catheter is inserted into a vein 22. Fluoroscopy,ultrasound, an angioscope imaging technique, or another technique may beused to direct and confirm the specific placement of the catheter in thevein. Impedance measurements can also be used to determine properpositioning of the catheter, particularly at the ostium of a vessel suchas at the sapheno-femoral junction. The impedance will be low when theelectrodes are in the blood stream. The catheter can then be moved untila high impedance value is obtained, indicating electrode contact withthe vein wall. The vein wall 80 has been compressed by the introductionof tumescent anesthesia into the tissue surrounding the vein asindicated by the arrows. The arrows in the figures indicate thecompression of the tissue. Unless stated otherwise, all drawing figureshaving arrows indicating tissue compression are not drawn to scale forpurposes of clarity of illustration and are meant to be representationsof the vein in a nearly fully occluded state.

The reduction in the vein 22 diameter caused by the tumescence of thetissue in contact with the treatment site assists in pre-shaping thevein to be molded to a ligated state. The compression also exsanguinatesthe vein and forces blood away from the treatment site, thus preventingcoagulation.

The actuator 76 (FIG. 4) is then operated to retract the outer sheath 94to expose leads the 100 and 104. As the outer sheath no longer restrainsthe leads, the primary leads 104 move outward relative to the axisdefined by the outer sheath, while the secondary lead 100 remainssubstantially linear along the axis defined by the outer sheath. Theprimary leads continue to move outward until their electrodes 108 areplaced in apposition with the vein wall 80 and the outward movement ofthe primary leads is impeded. The primary electrodes 108 contact thevein wall along a generally circumferential area or band of the veinwall. This outward movement of the primary leads occurs in asubstantially symmetrical fashion so that the primary electrodes 108 aresubstantially evenly spaced. Alternately, the electrodes 86 can bespaced apart in a staggered fashion such that they do not lie in thesame plane. For example, the adjacent electrodes 86 can extend differentlengths from the catheter so that a smaller cross-sectional profile isachieved when the electrodes 86 are collapsed toward one another.

When the electrodes 102 and 108 are positioned at the treatment site ofthe vein, the RF generator 50 is activated to provide suitable RFenergy. One suitable frequency is 510 kHz. One criterion used inselecting the frequency of the energy to be applied is the controldesired over the spread, including the depth, of the thermal effect inthe venous tissue. Another criterion is compatibility with filtercircuits for eliminating RF noise from thermocouple signals. In abipolar operation, the primary electrodes 108 are charged with onepolarity opposite that of the secondary electrode 102. The couplingbetween oppositely charged primary and secondary electrodes produces RFfields therebetween, and form a symmetrical RF field pattern along acircumferential band of the vein wall 80 to achieve a uniformtemperature distribution along the vein wall being treated.

The RF energy produces a thermal effect which causes the venous tissueto shrink, reducing the diameter of the vein 22. The thermal effectproduces structural transfiguration of the collagen fibrils in the vein.The collagen fibrils shorten and thicken in cross-section in response tothe heat from the thermal effect. As shown in FIG. 8, the energy causesthe vein wall 88 to collapse until further collapse is impeded by theprimary lead electrodes 108. The primary lead electrodes are pressedcloser together by the shrinking vein wall and assume a reduced profileshape which is sufficiently small so that the vein is effectivelyligated.

The catheter 90 is pulled back while continuing energy delivery as shownin FIG. 9. Ligation as the catheter is being retracted produces alengthy occlusion 89 which is stronger and less susceptible torecanalization than an acute point occlusion.

In a monopolar operation, the secondary-lead electrode 102 remainsneutral, while the primary electrodes 108 are commonly charged and actin conjunction with an independent electrical device, such as a largelow-impedance return pad (not shown) placed in external contact with thebody, to form RF fields substantially evenly spaced around thecircumference of the vein. The thermal effect produced by those RFfields along the axial length of the vein wall 80 causes the vein wallto collapse around the primary lead electrodes. The electrode device isretracted as described in the bipolar operation.

In either bipolar or monopolar operation the application of RF energy issubstantially symmetrically distributed through the vein wall, aspreviously described. The electrodes should be spaced no more than 4 or5 millimeters apart along the circumference of the vein wall 80, whichdefines the target vein diameter for a designed electrode catheter.Where the electrodes are substantially evenly spaced in a substantiallysymmetrical arrangement, and the spacing between the electrodes ismaintained, a symmetrical distribution of RF energy increases thepredictability and uniformity of the shrinkage and the strength of theocclusion.

Although not shown, in another embodiment, the primary leads may bemounted or otherwise configured such that they expand outwardly in anasymmetrical fashion. One purpose for an asymmetrical electrodearrangement is to only shrink a portion of the vein wall to achieveocclusion. Such may be desired in the case of preferentially shrinking atributary branch or aneurysm on one side of the vein.

After completing the procedure for a selected venous section ortreatment site, the actuator 76 causes the primary leads 104 to returnto the interior of the outer sheath 94. Once the primary leads arewithin the outer sheath, the catheter 90 may be moved to another venoussection where the ligation process is repeated.

As illustrated in FIGS. 10 and 11, another embodiment of an expandableelectrode catheter 118 includes two sets of expandable electrode leads120 and 122, although additional sets of electrode leads may bepossible. The electrodes 124 of this embodiment are similar to theelectrodes of the embodiment illustrated in FIG. 6 having electrodeswith a rounded, convex, spoon-shaped contact area. Other shapes for theelectrode may be used, such as ellipses, rounded, ovals, race tracks,and others. Although only one electrode is indicated by numeral 124 inFIGS. 10 and 11, this is for purposes of clarity in the drawings only.All electrodes are meant to be indicated by numeral 124. While each setof electrode leads may include as few as two electrode leads, theillustrated embodiment includes six electrode leads per set, althoughmore than six electrode leads may be used as well.

In the embodiment shown in FIGS. 10 and 11, the sets of electrode leads120 and 122 are longitudinally separated from each other. Thus, theelectrodes within each set of electrode leads are separated from oneanother radially and each of those electrodes is also separated fromevery electrode in the other set longitudinally, due to the longitudinalseparation. There therefore exists radial separation and longitudinalseparation of electrodes at the working end 126 of the catheter 118 inthe arrangement shown in FIGS. 10 and 11.

With the configuration of electrode leads presented in FIGS. 10 and 11,greater flexibility exists in establishing current flows through thetissue of a patient. As in previous embodiments, the electrodes expandoutwardly into contact with patient tissue. Where all the electrodes ofa first set of electrode leads have the same polarity, there may be anodd number of electrodes in the set, or an even number. All electrodesin the set may be connected to a common connection point, such as theconducting ring 106 shown in FIG. 6. A single conductor from theconnecting end of the catheter may power all electrodes of the set by asingle connection to that conducting ring. All electrodes of a secondset of electrode leads may also be commonly connected at a respectiveconducting ring but to a different electrical potential than the firstset. Because two different electrical potentials exist at the workingend of the catheter, energy will flow through the patient tissue betweenthose sets of electrode leads and a bipolar arrangement will exist.Thus, a length of patient tissue, at least as long as the distancebetween the first and second sets of electrode leads, will receive theenergy.

A monopolar arrangement may also be established if desired by settingall electrodes of all electrode leads to the same electrical potentialand establishing a different electrical potential outside the patient,such as at a “backplate” in contact with the skin of the patient at aselected location. Energy from the working end 126 of the catheter willthen flow through the patient to the return provided by the backplate.

In another arrangement in polarizing or controlling the electricalpotential at the electrodes, the electrodes in the first set ofelectrode leads may be individually controlled so that there areelectrode pairs of differing potentials in the set of leads. This wouldestablish a bipolar approach within the first set of leads itself. Ifthe electrodes of the second set of leads are likewise connected fordifferent potentials among themselves, they too would provide a bipolarapproach in their own set and currents would flow through patient tissuebetween the electrodes in each set of leads. If the electrodes having afirst polarity in the first set are aligned with the electrodes having adifferent polarity in the second set of leads, energy would not onlyflow between the bipolar electrodes within the set but would also flowto the electrodes in the other set resulting in two bipolar arrangementsat the single working end of the catheter. Patient tissue of a length atleast as great as the distance between the first and second sets ofelectrode leads will receive energy as well as patient tissue betweenelectrodes within each set of leads itself.

A further arrangement coupled with the bipolar approach just describedwould be to also use a backplate at a different electrical potential toprovide further control over the energy flow through the patient'stissue. In this case, energy would flow between the electrodes withineach set of leads, between electrodes in different sets of leads, andbetween electrodes and the backplate.

In yet a further arrangement, each of the electrodes may be individuallyconnected to a power source (50, FIG. 4) and the electrical potential ateach electrode can be individually controlled. This arrangement mayyield even more precise control over the current densities throughpatient tissue. As an example, where less current flow is desiredbetween certain electrodes of a set of leads but more current flow isdesired between those electrodes and electrodes of a second set ofleads, the potential between the electrodes of the same set may bereduced but the potential between those electrodes and the electrodes ofthe second set of leads may be increased resulting in the desiredcurrent flow densities. In the case where a backplate is also used, theelectrodes may be controlled so that energy flows between suchelectrodes and the backplate. Because each electrode is individuallycontrolled, the level of energy it imparts to the tissue at its locationis controllable.

One factor that could affect the number of electrodes per set ofelectrode leads is the diameter of the vein being treated. The design ofthe contact pad for the electrode leads could also affect the desirednumber of electrodes for a given procedure.

In this embodiment, the electrode leads 120, 122 are formed to expandoutwardly into apposition with the target tissue, yet as the targettissue shrinks, the electrodes maintain contact with that tissue and aremoved inwardly by that tissue. Because of this arrangement, the leadscompensate for variations in the diameter of the vein. They aretherefore capable of maintaining apposition with the tissue whether ornot compression of the vein or anatomical structure exists, such as byuse of a pressure cuff or tourniquet or tumescence of the surroundingtissue.

The tip 128 of the electrode catheter 118 should have a hemispherical oranother atraumatic shape. The tip 128 may be electrically neutral, andmay be fabricated from a polymer or it may be fabricated of stainlesssteel. Because the tip 128 has a rounded shape and is located at thedistal extreme of the catheter, it may perform a guiding function whenintroducing the catheter to the patient.

The double set of expandable electrodes can be used to ligate veins orother hollow anatomical structures in a manner similar to thatpreviously described. The outer sheath 130 can be pulled back to allowthe electrode to expand outwardly from the catheter and into appositionwith the wall of the lumen being treated. The two sets of electrodes 120and 122 apply energy to the lumen to cause it to shrink to a reduceddiameter. The catheter can be moved or pulled back while the energy isbeing applied to treat an extended area of the lumen. When the desiredarea of the lumen or vein is treated (e.g., ligated) energy is no longerprovided to the electrodes, and the outer sheath 130 is pushed forwardto force the expanded electrodes back to an unexpanded condition. Thecatheter can then be removed from the patient, or another section of thevein can be treated.

The description of the component parts discussed above are for acatheter to be used in a vein ranging in size from 3 mm (0.12 in) to 10mm (0.39 in) in diameter. It is to be understood that these dimensionsdo not limit the scope of the invention and are merely exemplary innature. The dimensions of the component parts may be changed toconfigure a catheter that may used in various-sized veins or otheranatomical structures.

Referring now to FIG. 12, there is shown a partial cross-section view ofthe catheter of FIGS. 10 and 11. Two pluralities of electrodes 120 and122 are shown with the electrodes of the first plurality 120 beingindicated by numeral 124 and the electrodes of the second plurality 122being indicated by numeral 150. Each electrode is formed from anelectrically-conductive electrode lead 152 and 154 respectively that iselectrically insulated along its length except at its distal end atwhich point no insulation exists thus forming the electrode. Each leadhas an outward bend (not shown). An inner tube 156 includes a lumen 158through which fluid may flow for flush or other purposes, or throughwhich a guide wire may be positioned. A hypotube 160 is positioned overthe inner tube and layers of insulation 162 are mounted over thehypotube. The first plurality 120 of electrode leads 152 extendproximally to a first mounting ring 164 to which all are connected. Thesecond plurality 122 of electrode leads 154 extend proximally to asecond mounting ring 166 to which all are connected. The rings 164 and166 are mounted over the hypotube insulation so that no electricalconduction path exists between the two. Wire conductors 168 and 170extend from the proximal end of the catheter to each ring so that allelectrode leads connected to a particular ring are interconnectedelectrically.

Alternate arrangements are possible and in one, alternating electrodesof a particular plurality are connected to two different rings. Eachring is separately connected to the power source and the polarities ofthe rings may therefore be made different to establish a bipolarapproach within the plurality. One electrode may be a “+” polarity whilethe two adjacent electrodes may be a “−” polarity. In this case then,there would be a total of three rings for all electrodes. In anotherarrangement, both pluralities would have two rings for its respectiveelectrodes with alternating electrodes connected to different rings sothat bipolar approaches within each plurality may be established. Inthis case, there would exist a total of four rings for the twopluralities of electrodes.

An outer movable sheath 172 when slid in the distal direction to thepoint shown in FIG. 12 will cause the electrode leads to contract to theposition shown. When slid in the proximal direction a sufficientdistance, the sheath 172 acts as a deployment device in that it willmove past the bend (not shown) in each of the electrode leads of thesecond plurality 122 permitting all electrode leads to expand outwardlyas shown in FIG. 11.

The electrode leads are formed of stainless steel in this embodiment andwith the thin insulation layer and the outward bend, have enoughstrength to automatically move outwardly through blood flow (in a venousapplication) and into apposition with the inner wall of the targettissue. As the inner wall shrinks due to the application of heat by theelectrodes, the inner wall will force the electrode leads toward theircontracted position but the electrodes will automatically stay inapposition with the inner wall during the entire ligation process due totheir outward bends and the material of which they are formed.

In one embodiment shown in FIG. 12, the electrode 124 includes atemperature sensor 54 and an electrode of the second plurality alsoincludes a temperature sensor 54. Although not shown as such, they aremounted flush with the outer electrode surfaces and their wires protrudeinwardly through the electrode and are held in place along therespective leads 152 and 154. In one embodiment, the microprocessor 52(FIG. 4) receives the signals from both temperature sensors, averagesthose signals and determines the effective temperature at the treatmentsite based on that average signal. Methods of averaging temperaturesignals are well known to those skilled in the art and no furtherdescription is provided here.

Although described above as positively charged, negatively charged, oras a positive conductor or negative conductor, these terms are used forpurposes of illustration only. These terms are generally meant to referto different electrode potentials and are not meant to indicate that anyparticular voltage is positive or negative. Furthermore, other types ofenergy such as light energy from fiber optics can be used to create athermal effect in the hollow anatomical structure undergoing treatment.Additionally, although the electrodes and leads have been described asprotruding from a distal orifice in the catheter, they may be expandedby other means and in other configurations. In another embodiments, theleads may be deployed by an inner pull wire, hydraulics, or magneticfields.

The benefits of tumescence would include locally anesthetizing thetreatment area for a prolonged period of time and insulating most of thesurrounding tissue and nerves from the damage of heat conducting fromthe treated vein. An additional benefit of the vasoconstriction inducedby the Epinephrine would be that the constricted blood vessels wouldlimit how fast the body absorbed the Lidocaine thus keeping the level ofLidocaine absorbed below the toxicity level. Also, as mentioned supra,extended applications of energy have a greater possibility of increasingthe temperature of the blood to an unacceptable level and may result ina significant amount of heat-induced coagulum forming on the electrodeand in the vein which is not desirable. Using a tumescent anesthesiacompression technique, including the administration of vasocontrictivedrugs, would aid in preventing this problem by exsanguinating the vein.

Although described above in terms of a vein, the concepts are generallyapplicable to other hollow anatomical structures in the body as well.The above description has been generally confined to veins inconsideration of avoiding unnecessary repetition.

While several particular forms of the invention have been illustratedand described, it will be apparent that various modifications can bemade without departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

1. A method of applying energy to a hollow anatomical structurecomprising the steps of: introducing a catheter having a working endpercutaneously into the hollow anatomical structure; advancing thecatheter within the hollow anatomical structure; positioning the workingend of the catheter at a treatment site within the hollow anatomicalstructure; administering fluid around the hollow anatomical structure atthe treatment site to cause the wall of the hollow anatomical structureto move towards the working end of the catheter; and applying energy tothe hollow anatomical structure at the treatment site from the workingend of the catheter.
 2. The method of claim 1, further comprising thestep of moving the working end of the catheter along the hollowanatomical structure during the step of applying energy.
 3. The methodof claim 1 further comprising the steps of: ceasing the step of applyingenergy; moving the working end of the catheter to a new treatment sitealong the hollow anatomical structure; applying energy to the hollowanatomical structure at the new treatment site from the working end ofthe catheter.
 4. The method of claim 1 wherein the step of applyingenergy includes the step of applying electrical energy.
 5. The method ofclaim 1 wherein the step of applying energy includes the step ofapplying RF energy.
 6. The method of claim 1 wherein the step ofapplying energy includes the step of applying microwave energy.
 7. Themethod of claim 1 wherein the step of applying energy includes the stepof applying light energy.
 8. The method of claim 1 wherein the step ofapplying energy includes the step of applying thermal energy.
 9. Themethod of claim 1 wherein the fluid thermally insulates the tissue nearthe treatment site.
 10. The method of claim 1 wherein the fluidthermally insulates nerve tissue near the treatment site.
 11. The methodof claim 1 wherein the fluid limits thermal damage to the tissue nearthe treatment site during the step of applying energy.
 12. The method ofclaim 1 wherein a sufficient volume of fluid is administered to causethe tissue surrounding the hollow anatomical structure at the treatmentsite to become tumescent.
 13. The method of claim 1 further comprisingthe step of extending electrodes from the working end of the catheter atthe treatment site before the step of applying energy.